FORT WORTH — A highly anticipated series of tests for air pollution around natural gas drilling sites in Fort Worth will start this month.

The City Council approved a $600,000 contract Tuesday with Eastern Research Group to conduct the tests and prepare a report due in March. The council approved a separate $50,000 contract at the end of July with Eastern, which was intended to fund preliminary testing work.

City officials say some of the tests will be unprecedented and could provide the best picture yet of how drilling in the Barnett Shale gas field affects the area's air pollution problem.

"This study is going to be a lot bigger than Fort Worth or Tarrant County," Mayor Mike Moncrief said. "They're going to be looking at this in other parts of the country where there are other shale plays."

The contract calls for the company to test every phase of gas development -- the drilling itself, well completions, hydraulic fracturing and pipeline operations.